Proc Filesystem

Proc Filesystem [T1003.007]

Information

• Name: Proc Filesystem

• ID: T1003.007

• Tactics: TA0006

• Technique: T1003

Introduction

Proc Filesystem (T1003.007) is a sub-technique within the MITRE ATT&CK framework under the OS Credential Dumping (T1003) category. Attackers leverage the Linux proc filesystem (/proc) to extract sensitive information such as credentials, command-line arguments, and environment variables from running processes. The proc filesystem is a virtual filesystem in Linux systems that provides an interface to kernel data structures, making it a prime target for attackers seeking sensitive runtime information.

Deep Dive Into Technique

The proc filesystem (/proc) on Linux is a virtual filesystem dynamically generated by the kernel. It provides detailed runtime information about system processes, hardware, and kernel parameters. Attackers can exploit this filesystem to gather sensitive information about running processes, including credentials, environment variables, command-line arguments, and memory mappings.

Technical details include:

• Process Enumeration: Attackers can enumerate running processes by listing directories under /proc, where each numeric directory represents a running process ID (PID).

• Credential Extraction: Files such as /proc/[pid]/environ and /proc/[pid]/cmdline can expose sensitive data, including passwords or API keys passed as command-line arguments or environment variables.

• Memory Dumping: Attackers may read /proc/[pid]/mem to extract memory content directly, potentially uncovering credentials stored temporarily in memory.

• File Descriptors Analysis: /proc/[pid]/fd/ directories contain symbolic links to files and sockets opened by the process, allowing attackers to understand process interactions and potentially escalate privileges or pivot laterally.

• Kernel and System Information: Files like /proc/version, /proc/cpuinfo, /proc/meminfo, and /proc/modules provide attackers detailed system information useful for further exploitation or privilege escalation.

Real-world procedures typically involve:

• Leveraging shell scripts or command-line utilities (cat, strings, grep) to quickly parse proc filesystem data.

• Automated scripts or malware that systematically scan /proc entries for sensitive information.

• Combining proc filesystem data with privilege escalation techniques to gain root access or lateral movement.

When this Technique is Usually Used

Attack scenarios and stages where attackers commonly use proc filesystem credential dumping include:

• Initial Reconnaissance: Attackers may use proc filesystem information to enumerate running processes, applications, and potential vulnerabilities or misconfigurations.

• Credential Harvesting: During privilege escalation or lateral movement, attackers target /proc entries to capture credentials that are temporarily stored or passed through command-line arguments and environment variables.

• Persistence and Lateral Movement: Attackers use information gathered from /proc to identify credentials or sensitive data enabling lateral movement across the network.

• Post-Exploitation Stage: After compromising a host, attackers leverage proc filesystem data to maintain access, escalate privileges, and evade detection by identifying security tools and processes running on the system.

How this Technique is Usually Detected

Detection methods, tools, and Indicators of Compromise (IoCs) include:

• Monitoring File Accesses: Tools such as auditd, Sysmon for Linux, or OSQuery can monitor and log access events to sensitive /proc files (/proc/[pid]/mem, /proc/[pid]/environ, /proc/[pid]/cmdline).

• Process Monitoring and Anomaly Detection: Security monitoring solutions like EDR (Endpoint Detection and Response) platforms can detect anomalous process behavior, including unusual process enumeration or memory access patterns.

• Behavioral Analytics: Implementing SIEM solutions (e.g., Splunk, ELK stack) to detect anomalous command executions involving proc filesystem interactions.

• File Integrity Monitoring (FIM): Monitoring and alerting on unexpected access to sensitive proc filesystem entries.

• Indicators of Compromise (IoCs):

  • Unusual or repeated access to /proc/[pid]/mem, /proc/[pid]/environ, /proc/[pid]/cmdline.

  • Command-line utilities (cat, strings, grep) executed against multiple proc filesystem entries in short timeframes.

  • Suspicious scripts or binaries accessing /proc files without legitimate administrative purposes.

Why it is Important to Detect This Technique

Early detection of proc filesystem credential dumping is critical due to the following impacts:

• Credential Exposure and Privilege Escalation: Attackers can obtain sensitive credentials, enabling privilege escalation or lateral movement across networks.

• Information Disclosure: Sensitive environment variables, command-line arguments, or memory content may include passwords, API keys, or tokens, resulting in unauthorized access to critical resources.

• Persistence and Further Exploitation: Information gathered from the proc filesystem allows attackers to maintain persistence, evade detection, and plan further attacks.

• System and Network Compromise: Failure to detect proc filesystem abuse can lead to complete compromise of systems, unauthorized data access, and potential data exfiltration.

• Compliance and Regulatory Risks: Undetected credential theft can lead to regulatory violations, compliance breaches, and significant reputational damage.

Examples

Real-world examples highlighting attack scenarios, tools used, and impacts:

• Attack Scenario: Credential Extraction via /proc/[pid]/environ

  • Attackers exploit misconfigured Linux systems to read environment variables containing sensitive credentials.

  • Tools Used: Standard Linux utilities (cat, strings, grep), custom shell scripts.

  • Impact: Compromise of sensitive credentials resulting in unauthorized access to databases, applications, or cloud environments.

• Attack Scenario: Memory Dumping via /proc/[pid]/mem

  • Attackers leverage elevated privileges or kernel vulnerabilities to dump process memory, extracting sensitive credentials or session keys.

  • Tools Used: Custom malware scripts, memory analysis utilities, or standard tools like dd and gdb.

  • Impact: Extraction of authentication tokens, passwords, and sensitive data, leading to privilege escalation and lateral movement.

• Attack Scenario: Process Enumeration and Information Gathering

  • Attackers enumerate processes via /proc to identify security tools (e.g., antivirus, EDR agents) or vulnerable applications.

  • Tools Used: Basic Linux commands (ps, ls, grep), automated malware scripts.

  • Impact: Identification of security defenses, enabling attackers to evade detection and tailor subsequent attack steps.

• Attack Scenario: File Descriptor Analysis via /proc/[pid]/fd

  • Attackers inspect file descriptors to identify open sockets, files, or network connections, facilitating lateral movement or data exfiltration.

  • Tools Used: Linux utilities (ls, lsof, readlink), custom enumeration scripts.

  • Impact: Unauthorized access to sensitive files, lateral movement, and data exfiltration through identified network connections.